It should be easy. As a teen-eager. What's funny or not. When I first went looking for information with regard to grades. There wasn't any. I asked the local hobby shop if they had any information and they handed me an Atlas booklet...for a dollar. Nothing in it except various track plans using their snap track. Really!! This is it. Okay, back to the Model Railroad wig wags (magazines) to see what I could learn. Remember they are the ones who don't know railroading. Obviously!! Then what? Kalmbach had a bunch of How To Books. I saved up my sheckles (money in the form of loose change) until I could buy a track planner type of book. Surely it would have grades and a simply put explanation. Not a chance in Hades or was that out near Twentynine Palms. You could feel the heat from hell but you couldn't see the location. Plenty of old volcanic craters around to prove hell once spewed it's ash and red hot sticky goo. Now what. Well you already know the rest of the story as told a few posts back. My mom's cloth measuring tape was never the same after that. Did you stretch it she asked? Well, yeah, kind of. I mean after all it's cloth. Go figure. Had to go buy her a new one. Yes, I kept the old one. Still have it I think. Each time I built a grade I learned something new. Some were a real stretch while others gave me nothing but fits. Still working on those switch panels. To many distractions and others wanting my attention, over the last few days. Back to work. More later!
Apparently some where along the way in our conversations we established that "2.355" is the number we need for appropriate clearance. I would concur with that. Despite the 1.75" clearance I referred to. I do appreciate Big Jake, Point 353 and Sharkman's participation here. You too George. You guys are the best. So onward and forward. Let's get some loops built. My helix is done but at a cost. I had to squeeze in the curves to get them to fit into the limited space restrictions. Originally a 9.50 by the same almost square metal shed. Often referred to as the Train Shed. I got a lot of railroading for such a small space. It was to be my last layout. Harrumph!! Now I have a little bit more room to stretch out. Not going to happen...yet!! Again, Later!
1.75" is the clearance you concluded you needed above the railhead on the lower track to clear the benchwork/roadbed that supports the track above. NMRA says that 1.73" should suffice. Close enough. I've always used 2.00". However, you need to factor in the height/thickness between the bottom of that benchwork/roadbed and the top of the railhead on the upper track. Big Jake estimated that value as 0.625", which added to 1.73" yields 2.355" from lower railhead to upper railhead. That's the total gain in elevation - top of lower railhead to top of upper railhead - that you need to use when calculating the radius for a given grade.
Good point, Point! If we assume a 270 degree, single turn, with a flyover at 90 degrees to the track underneath, the total length, from crossover to cross-under (or vise versa), in terms of the radius is 2R[the straights] + 3/4*2*pi*R [the 3/4 circle] which simplifies to 2R + 1.5*pi*R). Factoring out R gives us R*(2+1.5*pi). This becomes the "run" denominator in a slope or grade calculation (rise over run) So if you want a 2% grade, then the rise needs to be 2% of the run. Conversely, the run is 50x the rise. But unlike a helix, a 3/4 loop flyover can use a thru-truss bridge, which has much higher clearance for a given track height, since there's no plywood there (the plywood could still be used for the 3/4 circle.) So maybe we figure 0.25" "floor" thickness from bridge bottom to railtop. So, now we only need a total rise of 1.73 plus 0.25, or 1.98". Above, I said for a 2% slope, we need 50x the rise in track length from cross-under to cross-over. 50*1.98=99" Solving the above formula for run length in terms of R: 99" = R(2+1.5pi) R = 99"/(2+1.5pi) R = 14.75" If you want a larger R (radius), you're good, you'll have even less of a grade to climb! (the above is with a 2% grade) R is proportional to the total run (and thus inversely proportional to grade), so if you double the Radius to 29.5", you halve the grade to 1%) Or take the middle ground, so with 1.5x (3/2) the Radius (to 22.125"), you get 2/3 the 2% grade, or 1.33%.
I buy round corn bread and pies all the time. Square cakes, brownies and oblong bread. Gosh what happened to all the science going on here? i said with a big sheepish grin. Point 353, the 1.75 or 1&3/4 clearance is easy to work with when you divide it into linear feet to establish a 2% grade. Which translates into a 18.50 radius curve. Also good to hear NMRA recommends such. Still need to get my double stacks, autoracks and Hi-level passenger cars out to see it they will clear the flyover. The double stack being the tallest did pass through at one time. That being during original construction. So, I don't see a need to repeat it again. Looks like we've summed it up. Or this is the sum total of all the information shared. Wow, what math it takes to get to such figures. Now what are we going to tackle next? Thanks all for your participation.
Back to the switch panels. Cut here and then cut there. Pull out the switches and those lousy automated switch machines. I mean UGLY automated switch machines. More later!!
Just remember that the 1.75" dimension is the clearance from the top of the railhead on the lower track to the bottom of whatever is supporting the upper track. Before you start to "divide it into linear feet", you need to add to that 1.75" the thickness of the supporting structure for the upper track plus the height of the upper track (ties and rails) itself. Remember Big Jake's 0.625" factor that got us to 2.355". Otherwise, the double stacks will clout the support for the upper track and the owner of the container on top will be quite upset. Likewise, unless you want an abrupt change to/from level track to the 2% grade, you also need to account for the length of the transition sections. Otherwise, you'll end up with a "jump off ramp" or "a spot where your engine can be high centered or hang up on the rails." So, an 18.50" radius it really isn't.
I agree and think I said something similar earlier in a post. Proving we are both on track. However you said it better. Alright! Onward and forward.
I downloaded a picture here to see if things were still working. Rumor mill had it, you couldn't download a picture to Trainboard. I found everything normal all...the same. Worked just fine. Above is where I had to cut the layout in half to split it into easier section's. Hopefully making it easier to handle. Not so but more about that later. You can see all the wires that once ran all the way through to the other side. You guessed it: I get to put them back together, again. The humpty dumpty thing.
Back to grades for a minute or three. George, and I were talking on the phone and he reminded me of a method we both used on our layouts to aide with building our grades. Simple, actually. Take a one foot level, in length. Place a 1/4 inch wedge under on one end. Keeping in mind !/4 rise per linear foot or 12 inches = a 2% grade. When the level, levels out you have built yourself a 2% grade. By the way Harbor Freight and other hardware stores, has (last time I checked) a level that will do the job for you. Making it simple as a square pie. What? I didn't tell you about the square pie. I must have slipped up. It's called a Cobbler. Yummy!! Still, as in all in all. Thanks to all who have participated here and explained the math. You couldn't ask for better explanations. Job well done. Now back to the layout and the household current I need to connect to. You know, to power up my power tools. Batteries need to be charged. The only thing that hasn't changed is I'm still hooking up to household current to get the job done. I've got to say this. And the batteries never last long enough. Go figure!! Later all !!
"All the King's horses, and all the King's men" Are hoping you can put it together again! Said Big Jake. Well put!! "Mind the Gap," good one point 353!! The quote feature I probably screwed it up. Copy and paste works. Below is a picture of the stub end yard as it once looked. Right about now I'm wishing I knew about Kato's Switches. Way back when. Below: Today I gleefully removed the Atlas Switches. Tore the ... well ... out of them. It wasn't pretty. Now I have to figure out how to get a saw in there and cut the existing board. You'll understand this is the fun part. To the left of the picture. I need to cut flush right in front of the Atlas Flex Track and over the support below it. This is going to be tricky. Check out the wiring that will be in the way. Never mind the supports for the upper deck will be in the way. Did I say? And this is the fun part??? To the right of the picture. I did manage to remove a support board you can see underneath the Kato switch. We are off to a good start. Remodeling is never fun.
I don't have a router but I will take that under advisement. Looking at removing the board to get it out where I can cut it. While avoiding cutting the wire. If you get my drift. More to come after the break.
Rick my friend... You know I am always wiling to help so I am sending you what you really need... > THIS < No need to thank me...what are friends for.
If it were me, I would just put it back together, fix the wiring, and run trains. Shouldn't take any more than an hour or two. Doug
